Polymeric products, such as plastic packaging materials, plastic bags, and other plastic applications have become a serious environmental problem. It is estimated that each EU citizen uses an average of 200 plastic bags every year. The plastic bags are kept for an average of 20 minutes and it takes about 1000 years to degrade the plastic bags. About 4 Mtn on yearly basis of plastic material, particularly plastic bags, can be found in the seas and oceans, where it cause serious damage to the sea ecosystem. The new amendment to the EU waste directive and implementation of the directive on individual country level is targeting to reduce the usage of plastic bags to level of 90 bags per citizen by 2019 and further to 40 bags by 2025. Currently only about 6.6% of plastic bags are recycled and more than 8% ends up as litter. Thus environmentally acceptable, consumer preferred, recyclable and biodegradable substitute materials for plastic bags are needed.
Corresponding products traditionally made of paper, such as paper bags are also used. However, they have poor water resistance, they are relatively high in weight (e.g. in comparison to plastics), they are inflexible, their converting process is slow, they have poor user experience and preference, and they generally have limited strength properties, especially related to tear.
Further, plastic bags made of biodegradable plastic, such as polylactic acids or polymeric starch are available, but they have limited water resistance as well as user acceptance and strength properties. Starch products further compete with food production, which is a serious concern for the sustainability and land use.
CN101302319 describes biodegradable shopping bags made of a slurry comprising refined grass, wheat straw, bagasse, annual herb leaves and stems, polyvinyl alcohol, optional gypsum, salt, defoamer and water-proofing agent, where the slurry is poured in a mold, dewatered and dried to obtain a sheet, which is formed to a shopping bag.
Technique relating to methods for producing foam-laid fiber webs is known technology particularly in the field of manufacture of non-woven and tissue products. Fiber web is formed from a dispersion of fibers in a foamed liquid. A pulp or fiber furnish is first prepared in a pulper, followed by dewatering, mixing with a foam or foamable liquid containing a surfactant and water. The fibers are dispersed in the foam and the formed fiber-foam is deposited on a wire and the main portion of the liquid, which is essentially in the form of foam, is removed by a suction. This technique is disclosed in EP 481746. Surfactants may be of any suitable type, such as anionic, cationic, non-ionic and amphoteric surfactants. Additionally, wet-strengtheners, binders, creping chemicals etc. may be used. Surfactants used in the foaming process are generally regarded as having a negative influence on both the dry and wet tensile strength of a paper web.
Based on the above it can be seen that there exists a need to provide environmentally acceptable and biodegradable substitute materials for non-degradable plastics presently used in various applications, such as packaging, plastic bags, etc.